Editor’s Note: This article is the third in a multi-part series exploring the hidden science behind the decline of American lakes and reservoirs. Adapted from an educational video series (watch the full video here), this series aims to equip local communities, lake associations, and municipal leaders with the scientific knowledge needed to demand effective, long-term restoration strategies.
Have you ever reviewed a lake management plan that sounded incredibly promising, only to watch your lake continue to deteriorate year after year? You are not alone. Across the Finger Lakes region, communities are spending small fortunes on treatments that fail to deliver lasting results.
The New York State Department of Environmental Conservation (DEC) tracks Harmful Algal Blooms (HABs) closely, and their data tells a frustrating story: despite millions of dollars invested in watershed management and in-lake treatments, the blooms are becoming more frequent and more severe. The traditional playbook is simply not working.
This disconnect between spending and results has prompted a shift in how environmental authorities view lake management. The Environmental Protection Agency’s (EPA) Office of Water has increasingly emphasized the need for comprehensive, ecosystem-wide monitoring rather than just reacting to surface blooms. We can no longer afford to manage lakes based on superficial indicators that give the illusion of progress while the real problems deepen below.
In our previous articles, we explored the three root causes of lake decline – hypoxia, sediment nutrient recycling, and phytoplankton imbalance – and the three actions required to fix them. But how can a lake committee or local municipality know, before signing a contract, that a proposed management plan will actually address these root causes?
The answer lies in the data. To ensure your community’s money is well spent, you must demand that your lake managers measure what actually matters. Here are the three critical measurements you need to see before making any commitments.
Measurement #1: Full-depth dissolved oxygen data
A healthy lake needs oxygen to survive, but taking a single oxygen reading near the surface tells you almost nothing. You need to see full-depth dissolved oxygen data, tracked over time, especially during the hot summer months.
Real oxygenation means maintaining dissolved oxygen levels of at least 5 mg/L all the way down to the benthic margin – the critical zone at the very bottom where the water meets the muck. If the data shows that oxygen levels drop off in the deeper water, it means the bottom of your lake is a hypoxic dead zone. When the bottom is hypoxic, the sediment will continue to release phosphorus, fueling the next algae bloom.
Be wary of proposals that rely on conventional surface aeration systems. These systems often fail to reoxygenate the deep water and can even worsen cyanobacteria blooms by stirring up nutrient-rich sediment. Demand proof that any proposed system can deliver oxygen all the way to the bottom.
Measurement #2: Comparative bathymetric scans
The second metric you need is proof of sediment reduction. The muck at the bottom of the lake is a massive compost pile feeding the algae. Any effective management plan must reduce this nutrient stockpile.
However, claims about muck reduction are often poorly validated. Believe it or not, some contractors still use poles to poke into the soft sediment in a few random spots to estimate muck depth. This method is highly subjective, wildly inaccurate, and completely unacceptable for making major financial decisions.
Instead, demand comparative bathymetric scans. These are accurate, mapped acoustic measurements of the entire lake bottom, conducted over several years. You want to see detailed contour maps, lake profiles, and quantified data showing a measurable reduction in sediment volume. If a contractor cannot provide this level of data from past projects, they are unlikely to deliver it for yours.
Measurement #3: Detailed phytoplankton composition
The third critical measurement involves the algae itself. Most lake reports rely heavily on a metric called Chlorophyll-a to estimate algae levels. But relying solely on Chlorophyll-a is a dangerous blind spot.
Here is why: beneficial, healthy algae use Chlorophyll-a to photosynthesize. But toxic cyanobacteria (blue-green algae) primarily use a different pigment called phycocyanin. If a lake manager only measures Chlorophyll-a, it might look like algae levels are decreasing. In reality, the beneficial algae are dying off, while the toxic cyanobacteria are quietly taking over.
You need a detailed analysis of the phytoplankton composition. You need to know exactly what types of algae are in the water, not just a generic proxy measurement. What you don’t measure can be just as important as what you do.
Beware the unintended consequences of chemicals
Finally, you must understand the unintended consequences of the treatments being proposed. Algaecides kill all phytoplankton, but they are generally more effective at killing beneficial algae than toxic cyanobacteria. Furthermore, scientific research shows that cyanobacteria can quickly develop resistance to these chemicals.
Every time a lake is treated with algaecide, the beneficial algae are wiped out, while the cyanobacteria survive, adapt, and come back stronger. A report showing low Chlorophyll-a levels after an algaecide treatment is not a success story – it is a warning sign that you are opening the door for a toxic takeover.
The same logic applies to chemical herbicides used on aquatic weeds. They kill the plants, but the massive amount of dead, rotting biomass sinks to the bottom, depletes the oxygen, and adds to the nutrient-rich muck, guaranteeing a worse problem next year.
What to ask before you sign
It is common to receive thick lake reports filled with data on water clarity, pH, and conductivity. But if the report does not address the root causes – if the bottom is still hypoxic, the sediment is still accumulating, and the toxic blooms return every year – then that report is simply documenting the slow demise of your lake.
Before your community signs another lake management contract, ask the hard questions:
- Can you provide full-depth dissolved oxygen profiles from past projects?
- Do you use comparative bathymetric mapping to prove sediment reduction?
- Do you monitor detailed phytoplankton composition, or just Chlorophyll-a?
If a proposed plan cannot demonstrate success in fixing the root causes, it is time to look for a better solution. The Finger Lakes deserve management strategies that deliver real, sustainable recovery, not just another season of treating symptoms.
